Magnetic Resonance Spectroscopic Imaging (MRSI), which is described, for instance, in the article “MR Spectroscopic Imaging: Principles and Recent Advances” by S. Posse et al., Journal of Magnetic Resonance Imaging, 37(6):1301-25 (2013), can be used in vivo to measure spatially-varying metabolite concentrations for a range of atomic nuclei, including 1H, 13C, 15N, 19F, 23Na, 31P. The technique combines temporal data sampling with MR imaging techniques to generate localized spectra for individual voxel locations. These spectra can then be used to provide important clinical information in the form of metabolite maps or separate fat and water images.
Data acquisition is more time consuming than for conventional Magnetic Resonance Imaging (MRI) and a rapid technique is required for generating the spatially- and spectrally-encoded data sets in scan times that are suitable for routine clinical examinations. One such method is EPSI disclosed in, for instance, the article “Spatial mapping of the chemical shift in NMR” by P. Mansfield et al., Magnetic Resonance in Medicine, 1(3):370 to 386 (1984), but this technique is severely limited by a low spectral bandwidth, which is insufficient for many applications, particularly at high field strengths, at high spatial resolutions or for metabolites with a large range of chemical shifts.